Method of preventing interference of adjacent frequencies in a cellular system by selection between adjacent carrier frequency and non-adjacent carrier frequency

1. A method of preventing interference of adjacent frequencies in a cellular system comprising the steps of: at the mobile station: measuring received power of the carrier frequencies directed in the carrier selection rule information at the time the mobile station starts communication with the base station; reporting the measurement result to the base station using a non-adjacent carrier frequency that is not adjacent to the carrier frequency paired with the measured carrier frequency; at the base station: receiving the measurement result from the mobile station; selecting a non-adjacent carrier frequency if the measured received power is larger than a threshold value and selecting an available carrier frequency if the measured received power is equal to or smaller than the threshold value; sending a call-setup direction, and informing the mobile station of the selected carrier frequency; at the mobile station: starting communication using the selected carrier frequency; measuring received power of carrier frequencies as directed in the carrier selection rule information at a certain time interval, and reporting the measurement result to the base station; at the base station: receiving the measurement result from the mobile station; selecting a non-adjacent carrier frequency, and informing the mobile station of an inter-frequency handover direction, if the measured received power is larger than the threshold value and the mobile station is using an adjacent carrier frequency that is adjacent to the carrier frequencies paired with the measured carrier frequencies; and at the mobile station: starting inter-frequency handover to the selected carrier frequency.

2. A method of preventing interference of adjacent frequencies wherein first and second cellular systems, each comprising a plurality of base stations and at least one mobile station utilizing frequency bands adjacent to each other for an uplink channel are provided in a same service area, and a signal for the uplink channel used by a mobile station of the first cellular system may cause interference of adjacent frequencies to a base station of the second cellular system, said method comprising the steps of: at said mobile station of said first cellular system: measuring a received power of each of a plurality of carrier frequencies as directed in measurement information; and estimating a speed with which said mobile station is on the move, said step of estimating a speed including the steps of obtaining a median of a received power of a perch channel transmitted from the base station, and counting the number of times that the value of said received power crosses said median for a certain period of time; and at the base station and the mobile station of said first cellular system: if an estimated movement speed is larger than a threshold speed, using a carrier frequency that is not adjacent to the carrier frequency used when the estimated movement speed is larger than a threshold speed; wherein the first and the second cellular systems use CDMA (Code Division Multiple Access).

3. A method of preventing interference of adjacent frequencies wherein first and second cellular systems, each comprising a plurality of base stations and at least one mobile station utilizing frequency bands adjacent to each other for an uplink channel are provided in a same service area, and a signal for the uplink channel used by a mobile station of the first cellular system may cause interference of adjacent frequencies to a base station of the second cellular system, said method comprising the steps of: at the mobile station of said first cellular system: using, preferentially, a carrier frequency that is not adjacent to a carrier frequency of the uplink channel used by the second cellular system when a signal for the downlink channel is continuously received; measuring a received power of signals transmitted from a base station of the second cellular system when a signal of the downlink channel is intermittently received; and at the base station and the mobile station of said first cellular system: if the measured value is larger than a threshold value, using a carrier frequency that is not adjacent to that of said second cellular system as a carrier frequency of an uplink channel.

4. A method of preventing interference of adjacent frequencies wherein two cellular systems using a CDMA (code division multiple access) method comprising a plurality of base stations and at least one mobile station utilizing frequency bands adjacent to each other for an uplink channel are provided in a same service area, and signal for the uplink channel used by a mobile station of one cellular system may cause interference of adjacent frequencies to a base station of the other cellular system, said method comprising the steps of: at the mobile station of said one cellular system: measuring a received power of signals transmitted from the base station of the other cellular system; reporting the information about the measurement result to the base station of said one cellular system using a non-adjacent carrier frequency that is not adjacent to the carrier frequency paired with the measurement carrier frequency; and at the base station and the mobile station of said one cellular system: if the measured value is larger than a threshold value, using a carrier frequency that is not adjacent to that of said other cellular system as a carrier frequency of an uplink channel.

5. A method of preventing interference of adjacent frequencies in a cellular system comprising the steps of: at a mobile station: measuring received power of carrier frequencies as directed in measurement information, and reporting information about the measurement result to a base station; at the base station: receiving information about the measurement result from the mobile station; selecting a non-adjacent carrier frequency, and informing the mobile station of an inter-frequency handover direction, if the measured received power is larger than a threshold value and the mobile station is using an adjacent carrier frequency that is adjacent to the carrier frequencies paired with the measured carrier frequencies; and at the mobile station: starting inter-frequency handover to the selected carrier frequency.

6. A cellular system comprising: a plurality of base stations; and at least one mobile station for establishing an uplink channel and a downlink channel with one or more base stations to communicate therewith, measuring a received power of each of a plurality of carrier frequencies as directed in measurement information estimating a movement speed and if an estimated movement speed is larger than a threshold speed, using a carrier frequency that is not adjacent to the carrier frequency used when the estimated movement speed is larger than a threshold speed, said mobile station obtaining a median of a received power of a perch channel transmitted from the base station, and counting the number of times that the value of said received power crosses said median for a certain period of time, thereby estimating the movement speed; wherein said cellular system uses CDMA (Code Division Multiple Access).

7. A cellular system comprising: a plurality of base stations; and at least one mobile station for establishing an uplink channel and a downlink channel with one or more base stations to communicate therewith, using a carrier frequency not adjacent to a carrier frequency of another cellular system, preferentially at a time of receiving the downlink channel continuously, as a carrier frequency of an uplink channel, measuring a received power of each of a plurality of carrier frequencies as directed in measurement information at a time of receiving the downlink channel intermittently, and if a measure value of received power is larger than a threshold value, using a carrier frequency that is not adjacent to the carrier frequency having said measure value of received power.